DESCRIPTION: The long term goals of the proposed research are to determine how the olfactory system senses and discriminates odorants. The focus of the proposed research is to use molecular and cellular techniques to specify what molecules are being use to sense odorants and how detection of an odorant by an olfactory neuron is transmitted to higher order neurons in the olfactory bulb. The immediate goals of this proposal are: 1) To provide a comprehensive characterization of the zebrafish odorant receptor repertoire. It is estimated that the zebrafish genome encodes on the order of several hundred odorant receptors. 2) To provide a functional characterization of the ligand-activation properties of newly identified zebrafish odorant receptors. 3) To examine the role of olfactory neuron activity in the establishment of convergent connections between olfactory neurons and their glomerular targets in the olfactory bulb. These studies will use a genetic-based approach to elucidate the cellular and molecular mechanisms underlying olfactory coding and development. They will provide interesting information about the genomic organization of genes encoding olfactory receptors, what ligands bind and activate these gene products, and the requirements for olfactory neurons to properly project to their neuronal targets.